Weather Blog: Severe weather chances & pattern update

Thank you for stopping by the weather Watch 12 blog! Unsettled weather camps over Wisconsin for the next several days. In today's Weather Watch 12 blog we discuss thunderstorm chances and timing, plus look at the overall cycling weather pattern.

Let's start with the overall set-up that will lead to on and off thunderstorms and humid weather conditions the next several days.

A warm front nudges into southern Wisconsin this afternoon and evening. The WPC forecast surface map below shows the front over our area Thursday night at 1am. With the front near, scattered showers and thunderstorms are likely.

A few storms may have the potential to be strong to severe. The Storm Prediction Center has placed southeast Wisconsin in a slight risk for severe weather through early Friday morning.

The main threat with any storms in southeast Wisconsin is downpours that lead to rain totals quickly topping 1".

While a strong storm can't be completely ruled out Thursday afternoon, the best chance for strong storms arrives mainly between 6pm Thursday and 1am Friday. Clouds and rain cooled air in spots may limit the overall severe threat Thursday afternoon.

By this weekend a southwest flow aloft develops and pushes hot and very humid air into Wisconsin. Using our knowledge of the weather pattern and the cycle duration of around 57 days we can trace the wet weather and much warmer temperatures back to late June-July 1.

Let's start by looking at the forecast 500mb(middle of the atmosphere) map valid this Sunday at 7am. The map below has numbers labeled 1-3 to highlight the important features. Feature 2 is a ridge that will help draw warm/humid air into the Midwest.

Feature 3 is a trough which will eventually lead to more thunderstorm chances, then a cooldown.

Going back 57 days we can trace this part of the pattern to late June. The 500mb archive map below is from June 28, 2014. The features to compare to the map above are labeled 1-3. I always find this amazing!

The overall weather pattern should begin a transition in the next 6-8 weeks that will lead to a shift in the cycle duration, and new dominate features that will carry us through next summer. Make sure to check back to the Weather Watch 12 blog often as fall is an exciting time to keep a close eye on the emerging weather pattern.

For the latest weather information watch WISN 12 News, and for updates throughout the day follow me on Twitter @jnelsonweather